Informations about the Earth

2.  Earth is the third planet from the Sun and
the only object in the Universe known to
harbor life. According to radiometric dating
and other sources of evidence, Earth formed
over 4 billion years ago.
• Radius: 6,371 km
• Age: 4.543 billion years
• Surface area: 510.1 million km²
• Axial tilt: 23.4392811°
• Polar radius: 6356.8 km (3949.9 mi)
• Volume: 1.08321×1012 km3 (2.59876×1011 cu mi)

4. Let’s watch a short video clip about
the Layers of the EARTH.

5. The EARTH has three main
layers:

6. CRUST
• The crust is the outermost
layer. The thin parts are
the oceanic crust, which
underlie the ocean basins
(5–10 km) and are composed
of dense silicate igneous
rocks, like basalt. The thicker
crust is continental crust,
which is less dense and
composed of silicate rocks,
like granite.

7. MANTLE
• Earth's mantle extends to a depth
of 2,890 km, making it the
thickest layer of Earth. The
mantle is composed
of silicate rocks that are rich in
iron and magnesium relative to
the overlying crust. Although
solid, the high temperatures
within the mantle cause the
silicate material to be
sufficiently ductile that it can
flow on very long timescales.
Convection of the mantle is
expressed at the surface through
the motions of tectonic plates.

8. CORE
 This is divided into two parts:
• The outer core of the Earth is a liquid layer ,thick
composed of iron and nickel which lies above the
Earth's solid inner core and below its mantle.
• The inner core of the Earth, its innermost part, is a
primarily solid ball It is believed to consist primarily of
an iron–nickel alloy, and to be about the same
temperature as the surface of the Sun

9. History of Earth
• Earth is the only planet whose English name does
not derive from Greek/Roman mythology. The
name derives from Old English and Germanic.
There are, of course, hundreds of other names
for the planet in other languages. In Roman
Mythology, the goddess of the Earth was Tellus -
the fertile soil (Greek: Gaia, terra mater - Mother
Earth).